Originally Posted by
Savagewolf
Mountain bikes have wider tires which is often more comfortable than high pressure road bike tires are.
Mountain bike tires often have more tread than road bikes, which makes them a little bit more likely to not get a flat.
Mountain bikes are more upright than road bikes. You can see around you easier to avoid dangers.
The width of mountain bike tires means you are less likely to be affected by the terrain like small cracks or potholes
Most stores that sell bikes carry more mountain bikes than road bikes, and at a more affordable price.
Your mountain bike looks more like everyone elses bike, it doesn't stand out as much to a thief
Mountain bike frames are usually pretty stout things that can take a lot of abuse
With the exception of what I bolded, that's all post-hoc justification. The real answer is:
Originally Posted by
slowandsteady
Because they are cheap, readily available and multi-purpose.
And 'multi-purpose' is pushing it. In the 70s bike boom there were all kinds of reasons given why the 10-speed was ideal for riding around the neighborhood (skinny tires for efficiency!). In the 90s when mountain bikes became cool there were all kinds of reasons given why mountain bikes were ideal for riding around the neighborhood (cushy tires! jump potholes!). And now that fixed-gears are (were) cool there's plenty of reasons conjured up why they are ideal for riding around the neighborhood (simple! low maintenance!). These functional reasons have very little to do with why most people actually buy and ride these bikes.